condensation

This often attracts attention among online conspiracy theorists, who falsely claim that condensation trails in the sky – water vapour created from aircraft jet engines – is evidence of sinister large-scale geoengineering today.

"Viruses can be transmitted, and bacteria as well, by air conditioning systems because they cool air. That means you get condensation and you get water build-up unless the air conditioning system is well maintained."

So, “if you have a super steamy bathroom with condensation dripping down the mirror, avoid including anything valuable,” Elliott says.

They wore several layers of clothing and the tent was well ventilated so there was no condensation, he added.

Between the panes, evidence of condensation indicates the window seal had failed, allowing heat to escape.